This application incorporates the following patents and applications herein by reference: U.S. patent application Ser. No. 12/576,970 filed Oct. 9, 2009 entitled Valvuloplasty Catheter And Methods (now U.S. Pat. No. 7,951,111 issued May 31, 2011; U.S. patent application Ser. No. 10/846,613 filed May 14, 2004 entitled Valvuloplasty Devices And Methods (now U.S. Pat. No. 7,744,620 issued Jun. 29, 2010; U.S. patent application Ser. No. 13/231,807 filed Sep. 13, 2011 entitled Positionable Valvuloplasty Catheter; U.S. patent application Ser. No. 13/766,464 filed Feb. 13, 2013 entitled Ellipticity Measuring Device; U.S. patent application Ser. No. 14/452,426 filed Aug. 5, 2014 entitled Bulbous Balloon With Mechanical Pressure Regulator; and U.S. Patent Provisional Application No. 61/983,377 filed Apr. 23, 2014 entitled Echogenic Marker Bands.
Valvuloplasty balloon catheters have been used to post-dilate stented valves that have been placed via transcatheter aortic valve replacement (TAVR) procedures. A valvuloplasty balloon is placed within the stented valve and dilated after the TAVR device has already been delivered across the site of the stenotic native aortic valve. Such post dilation has been noted to place the stent structure into more direct contact with the surrounding tissue including the native aortic valve leaflets and calcium nodules associated with the leaflets, the aortic sinus, and left ventricular outflow tract (LVOT), and thereby reduce the amount of blood leakage around the perimeter of the stented valve.
For self-expanding (SE) TAVR devices the post dilation step can ensure that underlying tissue such as the native valve leaflets and calcium nodules are fully expanded or deformed via the post dilation valvuloplasty procedure. This tissue deformation provides not only improved area for blood flow through the replaced valve but also provides a reduction in perivalvular leaks (PVL) between the stent structure and the native aortic valve tissues.
For balloon expandable (BE) TAVR devices, post dilation may be performed less often than with SE stented valves; a post dilation of a BE device can provide a larger stent diameter, more stent deformation, and provide a greater deformation of the leaflet tissues and calcium deposits underlying the stent structure. Such deformation of the BE stent can place the stent into more intimate contact with the native tissues along a perimeter of the stent resulting in a reduction in perivalvular leaks.
The native annulus can be generally interpreted as a narrowing in the aortic root located at the base of the native valve leaflets; the annulus is positioned at the base of the aortic sinus adjacent the left ventricular outflow tract (LVOT). Post dilation of a TAVR device with a cylindrical balloon is limited due to the inability to deform the native leaflets and other restrictions on either side of the native valve annulus without applying undue excessive forces upon the annulus that can lead to annular rupture or dissection. What is needed is a balloon that can post dilate a TAVR device by deforming the native valve leaflets and other restrictive tissues located outside of the TAVR stent structure while ensuring that the native annulus is not exposed to excessive forces that can cause the annulus to rupture or dissect; such a balloon would contribute to greater reduction of PVL and would provide additional safety to the patient by reducing the likelihood of annular rupture.
Stand-alone balloon aortic valvuloplasty (BAV) and transcatheter aortic valve replacement (TAVR) are performed to treat patients suffering from aortic valve stenosis. The BAV procedure can also performed prior to the TAVR procedure as a pre-dilation prior to delivery of the TAVR device or after implantation of the TAVR device as a post-dilation to reduce the amount of perivalvular leakage; BAV also provides a bridge to a TAVR procedure that can be initiated at a later date. During the implantation of the TAVR device it is important to place a TAVR device that has the correct diameter, i.e., one that provides an appropriate diametric fit with the aortic valve annulus. Additionally, it is important to locate the TAVR device along the axis of the aortic sinus such that it is in proper axial position with the basal ring or plane containing each nadir for each of the three native valve leaflets. Further, it is important to identify the angle of the axis of the aortic sinus (sinus of Valsalva) and align the TAVR device such that it is in alignment with the axis of the aortic sinus.
Typically a CT scan is performed prior to the TAVR procedure to identify the diameter of the annulus and examine the suitability of the patient for the TAVR procedure. CT measurement of the annulus diameter is not performed in real time and is not performed under a stretched condition such as found during the implantation of the TAVR device; the presence of calcium can make it difficult to accurately measure the true diameter of the annulus. The orientation of the plane of the basal ring and the axis of the annulus is difficult to identify accurately using CT scan alone.
Often transesophageal echo (TEE) or transthoracic echo (TTE) is used to visualize the aortic annulus and determine its diameter in order to properly size the TAVR device that is to be implanted. Due to the ovality of the annulus and inaccuracies in identifying the axis of the aortic sinus and the proper location of the basal plane of the annulus, an error in the diameter measurement for the aortic annulus can exceed 2-3 mm.
What is needed is a device that can accurately locate the plane of the basal ring of the annulus and identify an accurate stretch diameter of the annulus to allow accurate sizing and placement of the TAVR device in real time. Such a device can also be used to measure a diameter of any tubular member in the body in real time using 2D or 3D echo. For example, the device can be used to accurately measure the diameter of other annuli of the heart, measure diameter of a blood vessel, or the diameter of any tubular member of the body.